This invention relates to thermal and noise insulation of the axial end walls of heated or cooled temperature controlled rotary cylinders, as for example the type of rotatable cylinders used in the paper manufacturing industry, and more particularly to the mounting of the insulation blanket to the cylinder end wall.
In the process of manufacturing paper products, wet paper is moved in a web about a plurality of heated rotary cylinders, and the heated cylinders progressively dry the paper. The rotary dryer cylinders can be heated from various heat sources, with a common heat source being superheated steam at a temperature sufficient to heat the cylindrical convex surface of the dryer cylinder to the desired temperature, usually between 100.degree. F.-600.degree. F. The steam is transmitted under pressure through the axles of the dryer cylinders to heat the inside of the dryer cylinders.
Since the web of paper makes continuing contact with the external convex surfaces of the dryer cylinder walls during the operation of the dryer cylinders, a major portion of the heat applied to the cylindrical wall of each dryer cylinder is absorbed by and taken away by the paper; however, the web of paper does not contact the axial end walls of the dryer cylinders, and the heat from inside each dryer cylinder that is transferred through its axial end walls is lost to the atmosphere.
Some attempts have been made to insulate the axial end walls of heated dryer cylinders. For example, the prior art discloses mounting a pair of semi-circular rigid insulator panels with clamps to the connector screws of the axial end walls of a dryer cylinder. Supporting a rigid insulator panel in two halves at the end of a rotatable dryer cylinder is believed to be somewhat hazardous since the halves may tend to part under the stress of centrifugal force and fly off of the rotary cylinder. Moreover, the attachment of clamps to single ones of the end wall connector screws is also believed to be hazardous because the clamps may fail.
While it appears that external heat shields can be applied to the external surfaces of a rotatable dryer cylinder by mounting the heat shields to the connector screws that attach the axial end walls to the cylindrical wall of the dryer cylinder, the connector screws must contain the axial end walls in position against the force of the high pressure super-heated steam within the dryer cylinder, and the loosening or otherwise adjusting of the connector screws might result in a safety hazard due to the connector screws parting from the dryer cylinder during rotation or due to steam leakage between the cylindrical wall and the axial end wall of the dryer cylinder. Additionally, many of the dryer cylinders which contain fluid under pressure are regulated by ASME pressure vessel codes. Therefore, the connectors used to mount insulators to the end walls of heated dryer cylinders must not alter the position of the connector screws or otherwise modify the ability of the connector screws to function in accordance with their specifications.